What is the key for the curve modifier to work properly?
It will simplify if you set the origin of both your objects to their geometry (right click and Set Origin to Geometry)
Once done, put the 2 objects at the same location (select one object, press ShiftS &gt; Cursor to Selected, select the other object and ShiftS &gt; Selection to Cursor)
Create some edge loops all along your tube if you want it to bend
Give it the Curve modifier with the curve as Object